Antiviral agents

The choice of antiretroviral agents to include in the initial regimen used in HIV-infected individuals who are treatment naive (have not previously received antiretroviral therapy) and the most appropriate agents to use in subsequent regimens in previously treated individuals must be individualized based on virologic, immunologic, and clinical characteristics of the individual patient.

Effective management of the disease must be based on updated information related to the biology and pathogenesis of HIV infection, currently available antiretroviral agents, clinical status of the patient.

Antiretroviral agents are synthetic antiviral agents that have antiviral activity against human immunodeficiency virus (HIV) and are used in the management of HIV infection. There currently are 5 different classes of antiretroviral agents commercially available: nucleoside reverse transcriptase inhibitors (NRTIs), HIV protease inhibitors, nonnucleoside reverse transcriptase inhibitors (NNRTIs), nucleotide reverse transcriptase inhibitors, and HIV fusion inhibitors.

The most frequently reported adverse effects with amantadine are similar to those observed with rimantadine and include adverse CNS and GI effects; however, amantadine is associated with more frequent and/or severe nervous system effects than rimantadine, including in geriatric adults. Adverse effects associated with amantadine usually are mild and are reversible upon discontinuance of the drug.

Amantadine hydrochloride is administered orally as a single daily dose or, preferably, in 2 equally divided doses to minimize transitory adverse effects. It has been suggested that if insomnia occurs, the last daily dose should be taken several hours before retiring.

Amantadine hydrochloride is used for symptomatic treatment and for prophylaxis of signs and symptoms of infection caused by various human and animal or avian strains of influenza A virus. While chemoprophylaxis with the drug should not be considered a substitute for annual vaccination with influenza virus vaccine, antiviral agents are critical adjuncts to influenza vaccine for the control and prevention of influenza.

Administration of amantadine in patients receiving drugs with anticholinergic activity may result in increased adverse anticholinergic and CNS effects. When amantadine is administered to patients already near the limit of tolerance for anticholinergic agents, atropinism with nocturnal confusion and hallucinations may gradually develop. It has been suggested that the dosage of the anticholinergic agent be reduced prior to the initiation of amantadine therapy or that the dose of either drug be reduced if atropine-like adverse effects appear.

Aciclovir is an anti-viral drug and it is active against the viral infections described under ‘USES’ below. Aciclovir Powder for Infusion 250mg may be used against certain viral infections.

Ribavirin is indicated in the treatment of carefully selected hospitalized infants and young children with severe lower respiratory tract infections due to respiratory syncytial virus (RSV). In addition, ribavirin (600 to 1800 mg / day for 10 to 14 days) has shown effectiveness in acute and chronic hepatitis, herpes genitalis, measles, and Lassa fever. The antiviral mechanism of action of ribavirin relates to alteration of cellular nucleotide pools and inhibition of viral messenger RNA synthesis. Intracellular phosphorylation to the mono-, di-, and triphosphate derivatives is mediated by host cell enzymes.

Lamivudine is a nucleoside reverse transcriptase inhibitor, which inhibits replication of HIV and hepatitis B virus (HBV). HIV infection: Epivir is used in combination with other antiretroviral agents for the treatment of HIV infection.